Spinal Cord Group, Institute of Neuroscience and Psychology, College of Medicine, Veterinary Medicine and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
Neuroscience. 2012 Dec 13;226:253-69. doi: 10.1016/j.neuroscience.2012.09.015. Epub 2012 Sep 16.
Spinocerebellar tract neurons are inhibited by various sources of input via pathways activated by descending tracts as well as peripheral afferents. Inhibition may be used to modulate transmission of excitatory information forwarded to the cerebellum. However it may also provide information on the degree of inhibition of motoneurons and on the operation of inhibitory premotor neurons. Our aim was to extend previous comparisons of morphological substrates of excitation of spinocerebellar neurons to inhibitory input. Contacts formed by inhibitory axon terminals were characterised as either GABAergic, glycinergic or both GABAergic/glycinergic by using antibodies against vesicular GABA transporter, glutamic acid decarboxylase and gephyrin. Quantitative analysis revealed the presence of much higher proportions of inhibitory contacts when compared with excitatory contacts on spinal border (SB) neurons. However similar proportions of inhibitory and excitatory contacts were associated with ventral spinocerebellar tract (VSCT) and dorsal spinocerebellar tract neurons located in Clarke's column (ccDSCT) and the dorsal horn (dhDSCT). In all of the cells, the majority of inhibitory terminals were glycinergic. The density of contacts was higher on somata and proximal versus distal dendrites of SB and VSCT neurons but more evenly distributed in ccDSCT and dhDSCT neurons. Variations in the density and distribution of inhibitory contacts found in this study may reflect differences in information on inhibitory processes forwarded by subtypes of spinocerebellar tract neurons to the cerebellum.
脊髓小脑束神经元受到来自下行束和外周传入的各种输入源的抑制。抑制作用可用于调节传递到小脑的兴奋性信息。然而，它也可以提供关于运动神经元抑制程度和抑制性前运动神经元运作的信息。我们的目的是将以前对脊髓小脑束神经元兴奋的形态学基础的比较扩展到抑制性输入。通过使用针对囊泡 GABA 转运体、谷氨酸脱羧酶和 gephyrin 的抗体，将抑制性轴突末端形成的接触鉴定为 GABA 能、甘氨酸能或 GABA 能/甘氨酸能。定量分析显示，与脊髓边缘 (SB) 神经元上的兴奋性接触相比，抑制性接触的比例要高得多。然而，与位于 Clarke 柱 (ccDSCT) 和背角 (dhDSCT) 的腹侧脊髓小脑束 (VSCT) 和背侧脊髓小脑束神经元相关的抑制性和兴奋性接触的比例相似。在所有细胞中，大多数抑制性末端是甘氨酸能的。与 VSCT 神经元的胞体和近端树突相比，SB 神经元的抑制性接触的密度在胞体和近端树突上更高，但在 ccDSCT 和 dhDSCT 神经元中分布更均匀。在这项研究中发现的抑制性接触的密度和分布的变化可能反映了脊髓小脑束神经元的亚型向小脑传递的抑制过程的信息差异。
